Embodiments of the present disclosure relate generally to the cooling of turbomachinery. More specifically, the present disclosure relates to a cooling supply circuit, including related turbine wheels and gas turbine systems.
FIG. 1 shows a schematic view of a conventional gas turbine assembly T. A gas turbine is a type of internal combustion engine in which compressed air is reacted with a fuel source to generate a stream of hot air. The hot air enters a turbine section and flows against several turbine blades to impart work against a rotatable shaft. The shaft can rotate in response to the stream of hot air, thereby creating mechanical energy for powering one or more loads (e.g., compressors and/or generators) coupled to the shaft. Combustors T1, connected to fuel nozzles T2, are typically located between compressor T3 and turbine T4 sections of gas turbine assembly T. Fuel nozzles T2 can introduce fuel into combustor T1 which reacts with compressed air yielded from compressor T3. Air T5 flows sequentially through compressor T3, combustor T1, and lastly through turbine T4. Work imparted to rotatable shaft T6 can, in part, drive compressor T3. Other forms of turbomachinery besides gas turbines (e.g., gas turbine assembly T) may feature a similar arrangement of components.
Turbine T4 typically includes a rotatable shaft T6 and various turbine wheels mounted circumferentially thereon. In the example of a gas turbine system, these components may experience high temperatures during operation. In some cases, these temperatures may cause certain components of gas turbine assembly T to wear out over time. The effects of high temperature in a gas turbine can be offset with a positive purge system. A positive purge system can include a source of cooling air, sometimes yielded from the compressor, which is fed axially into turbine T4. The cooling air in a positive purge system can be directed throughout turbine T4 to cool various components of a turbomachine.
In FIG. 2, a cross section of a conventional turbomachine 10 and turbine wheel 12 is shown. Turbine wheel 12 may be positioned circumferentially about a rotor 14 and can have a substantially annular shape. Turbine wheel 12 and rotor 14 are shown in FIG. 2 as being substantially oriented along an axial axis A with a radial axis R extending therefrom. Several turbine buckets 16 can be radially coupled to turbine wheel 12 and extend substantially in the same direction as radial axis R. Turbine wheelspaces 18 can be positioned between each turbine bucket 16 and turbine wheel 12. Turbine buckets 16 may increase in temperature while rotor 14 and turbine wheel 12 rotate during operation.
Several channels 20 may extend radially from rotor 14 through a body 22 of turbine wheel 12. A portion of rotor purge air 24 travelling along rotor 14 can enter channels 20 to pass through body 22 toward turbine buckets 16 and turbine wheelspaces 18. Body 22 can be coupled to wheel 12 by any currently known or later developed form of mechanical coupling, such as a fastener, a lock, a coupling mechanism, etc., with an example shown in FIG. 2 as a bolt circle 26. Bolt circle 26 can extend in a particular direction (e.g., parallel to axial axis A) through turbine wheel 12 and body 22 to prevent body 22 from being radially displaced during operation. Each channel 20 can provide fluid communication between a hollow interior 28 and a radial exterior 30 of turbine wheel 12, and may travel around or past bolt circle 26. Rotor 14 can be positioned within hollow interior 28 of turbine wheel 12, while turbine buckets 16 and turbine wheelspaces 18 can be coupled to radial exterior 30.